Ford Automobiles Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
I've read everything I can on this, and come up with no exact same problem. Mondeo, Mk4 2.0 tdci, 133000 miles

Here's a summary: drove home from France on saturday (about 550 miles, mainly fast motorway). No problems.

Monday morning, started car and drove to work. When the car got to normal temp, I got a "blocked diesel filter" message, and a minute or two later a "engine malfunction" message.

I took this to mean that the car had tried to do a regen on the DPF, but couldn't, for some reason.

It's done the same thing each time I've driven it monday and today.

We hooked it up to a friends diagnostic computer this evening, and fault codes showed blocked dpf. Pressure differential across DPF with engine running of 2.1 kPa. Pressure differential with ignition on, but engine off, 0.0 kPa.

We cleared the fault codes, tried a forced regen, which seemed to spend 20 mins doing nothing. We again cleared the fault codes, and switched off. On restarting, same errors.

Now, here's the puzzling bit. We stopped the engine, and cleared all the error codes. Turned the ignition on, and the "blocked diesel filter" message popped up again. Now, my question is - how can the car have detected a full DPF with the engine off ? No pressure differential across the DPF, surely the car doesn't know it needs a regen, until the engine is running.

So, do we suspect a faulty differential pressure sensor ?

( I can't see how it can be the hoses, as with the engine not running, they should both be at atmospheric pressure, and indeed the readings showed 0.0 kPa differential...)

Advice please ? Do I shell out on a new sensor and see if that cures it ?
 

·
Registered
Joined
·
101 Posts
Can you post the codes? I wouldn't replace the sensor just yet. At least check first the sensor hoses for damage or blockage then test the sensor with a pressure gauge and diagnostic tool that it reads correctly.

Does your model have a fuel vapouriser in the DPF?

DPF learned values might be the reason for the error without the engine running so try clearing that too. Presumably it has some memory of accumulated soot because the pressure sensor values don't rise until a regen happens then go back down.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #3 ·
Sorry, forgot to say, we did reset of the learned values.

I'll need to get it up on a ramp to look at the hoses, but main issue is that it throws the fault code with the engine off - which doesn't seem to make sense, as it can't be measuring a pressure difference, surely ?

AFAIK it does have a fuel vaporiser, yes. I've checked the fuse, all ok there.
 

·
Registered
Joined
·
459 Posts
Sorry, forgot to say, we did reset of the learned values.

I'll need to get it up on a ramp to look at the hoses, but main issue is that it throws the fault code with the engine off - which doesn't seem to make sense, as it can't be measuring a pressure difference, surely ?

AFAIK it does have a fuel vaporiser, yes. I've checked the fuse, all ok there.
Even though the fuse is intact it won't mean the vapouriser is working correctly had regen problems with mine, it kept trying to regen every so often and failing, the reason what apparent when i took the vape out it was only letting a trickle of fuel through and was nigh on fully blocked, the dpf was probably hanging on just from the passive regen cycle from the motorway, take it out if its seen the quoted miles i would honestly say its the culprit and well on the way to full blockage, the glow plug is protected by a thermal relay and only normally blows the fuse when its open circuit and shot.
 

·
Registered
Joined
·
583 Posts
just to throw a proverbial spanner in the works, but you say the 'blocked diesel filter' message came up. could it be thatits NOT dpf related, and it genuinely IS the DIESEL filter?? i would have expected a DPF message to say that the DPF filter was blocked, not the diesel filter, but i could be wrong!!

(either way, its just a thought and doesn't cost a fortune to try!)
 

·
Registered
Joined
·
459 Posts
just to throw a proverbial spanner in the works, but you say the 'blocked diesel filter' message came up. could it be thatits NOT dpf related, and it genuinely IS the DIESEL filter?? i would have expected a DPF message to say that the DPF filter was blocked, not the diesel filter, but i could be wrong!!

(either way, its just a thought and doesn't cost a fortune to try!
Good point forgot about that one, 2.0 have the facility to show that where as the 2.2 like mine won't it just comes up with fuel pressure low, GOOD SKILLS
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #7 ·
Hmmm. Interesting thought... Can I find out the exact wording of the dash message that relates to diesel or dpf filter from anywhere ?

Or if I rescan tonight and post the fault codes, will that let anyone tell me for sure ?

I did have the fuel filter changed just before summer (about 3000 miles ago...)

If the diesel filter (not dpf) is blocked what's the best plan ?
 

·
Registered
Joined
·
459 Posts
Hmmm. Interesting thought... Can I find out the exact wording of the dash message that relates to diesel or dpf filter from anywhere ?

Or if I rescan tonight and post the fault codes, will that let anyone tell me for sure ?

I did have the fuel filter changed just before summer (about 3000 miles ago...)

If the diesel filter (not dpf) is blocked what's the best plan ?
Normally they throw up a code only for blocked dpf the diesel filter blocked message would explain why its still coming up when the engines not working, the flow rate is monitored by a sensor on the fuel line, many of the cars on our fleet especially the ones with the filter housing at the back have suffered the same problems, premature blocking even after a service. My theory is where its mounted so close to the tank it drags more crap than normal up from the tank, i think they were aware of this which would explain why they spent more money on a fancy aluminium casting to house the fuel filter at the front of the engine on the later cars, Turbo Pete was spot on with the inexpensive change the filter first, my moneys on that one
 

·
Registered
Joined
·
459 Posts
P.S. if the filters at the front i have seen them collapse before their time, normally a rubbish after market filter off eBay or Eurocarparts, i had what was allegedly a Mann filter for my 2.2 it went within 2k so now i only buy from my local spares shop they are dearer but are genuine Mahle, that was two years ago and i haven't had a problem since bearing in mind the car gets serviced about six times a year
 
1 - 9 of 9 Posts
Top